The chief marketing officer of the world’s largest advertiser, Unilever, has said that ad blocking has come about because people find digital advertising irritating, and so advertisers and agencies need to rethink how they communicate with consumers on mobile devices.

Talking on CNBC’s new advertising show Marketing.Media.Money, Keith Weed, who has led Unilever’s marketing function globally since 2010, described as “exciting” the possibilities brought about by automated advertising, but on the topic of ad blocking said it was a “big challenge” for publishers and advertisers.

“All media, the free media, is paid for by advertising,” Weed told CNBC anchor Julia Chatterley in the interview. “And, of course, if that advertising stream goes elsewhere … then the quality of that content will go down. Less funds, less quality content. So it is a challenge for the industry,” he said, placing blame for ad blocking with advertisers and their agencies.

“Because why do people block ads? They block ads because they’re irritating in some form or other. So we’ve got to find better ways of making great content that really engages people.”

Weed said there was a “think-do gap” in the mobile marketing industry; a lot of talk but little action to change the status quo.

“A lot of advertising agencies, media companies and brand advertisers like ourselves talk a lot about mobile. Everyone talks about mobile. There are more mobiles on the planet than people, there are two billion smartphones and the next billion people who come online will be on mobile, I can give you mobile stats until you’re red in the face,” he said.

“However, what we’re talking about and doing on mobile is very different. I can show you some fantastic creative ads on TV and cinema, and then you get to mobile… we really haven’t cracked it.”

Also on the show was former M&M editor and founder of media company CSquared, Charlie Crowe, who challenged Weed on Unilever’s approach to digital marketing (to watch the clip, click here), picking out e-commerce as a strategic weakness that contributed to a downgrade in the company’s stock by Goldman Sachs, and questioning the leadership Unilever is showing in tackling issues such as ad fraud.

Weed defended Unilever’s track record in e-commerce, which Crowe had highlighted for being a slow and lacking in a centralised approach to data, saying “we’re very much on the front foot.”

When pressed by Chatterley on whether he thought Goldman Sachs and Crowe were both wrong in thinking Unilever has been slow to embrace e-commerce, Weed said: “Well at the end the day I’m a bit closer to it than either of them so I don’t think it’s a limitation. I do think that right now it’s a big fast growing area across the whole of consumer goods.”

Weed pointed to Unilever’s early interest in Silicon Valley and its partnerships and campaigns with Facebook, Google and Twitter as evidence that the company was “ahead of the game” and moving “at the right pace” in digital, and said Unilever was “in a very good place” regarding e-commerce.

On ad fraud, Weed referred to a survey where Unilever – which as Crowe pointed out now spends half of its marketing budget on digital in the US – had performed well.

He later said, “we have 10 different ways of checking everything and I think in that case you’ve got nothing to fear. If you buy it badly, you’ve got everything to fear.”